If you want to eliminate the voiding issue and have a quick check if the part is soldered...try putting some vias in the grnd pad....Make sure you get solder into the vias...3 to 4 mils of solder in the vias should compensate electrically and thermally for the missing copper generated by the holes... Paul Edwards Process Engineering [log in to unmask] Tel: 408-433-4700 FAX: 408-433-9988 Surface Art Engineering 81Bonaventura Dr. San Jose, CA 95134 DUNS: 944740570 CAGE/NCAGE: 1XZ48 -----Original Message----- From: Jason Gregory [mailto:[log in to unmask]] Sent: Tuesday, October 05, 2004 6:16 AM To: [log in to unmask] Subject: Re: [TN] Solder pad under chip Sounds like possibly the pad was not in the solder paste layer and wasn't cut. As far as inspecting, I had to do this in a former life. We inspected the pad with a 5DX, but not just for the presence of solder, but for solder coverage percentage. It was in the specs to ensure 70% solder coverage. I also learned alot about vacuolar porosity. You might want to inspect a sample every 10 boards or so with X-ray.....if you have the ability. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Bob Wilson Sent: Monday, October 04, 2004 3:01 PM To: [log in to unmask] Subject: [TN] Solder pad under chip Hi! I have a chip on a board (Linear Technology part number LTC3414) found here: http://www.linear.com/pdf/3414f.pdf It has a pad (pin number 21) that is underneath and a note that says: "To maximize the thermal performance of the LTC3414, the exposed pad should be soldered to a ground plane." I built the footprint and made sure the pad was soldermasked and included the pad shape in the pastemask file. The engineer was trouble-shooting and de-soldered the part from the board. It looks like there was no solderpaste or solder on the pad. Here's the (dumb) designer question: How would the solder get to that pad underneath? Should we add a requirement note saying that the part should be inspected or x-rayed to see if the pad is indeed soldered? Thanks for all and any suggestions. Regards, Bob Wilson www.cstone-design.com [log in to unmask] --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------