Hi Mark,

Just from my experience after having done a lot of these, the vias are always: uncovered, un-filled but allowing vendor to plate shut, 12 mil hole, tied to all planes & fills of same net, buried in plane.  I always check the documentation on the part to make sure it is not violating any recommended guidelines of course.  I hope your data converges on a good answer for you.

Richard Hatano
Tech. Mgr.
Dallas Electronics Inc.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mark Larson
Sent: Wednesday, August 31, 2011 12:52 PM
To: [log in to unmask]
Subject: [TN] QFN with solder slug

I am curious how others are handling these parts for soldering. Do you leave the thermal vias in the slug covered or uncovered with solder mask? Do you fill with anything? What size hole on a 62 mil board? Tie to all GND planes or just the back side? Thermal relief the via or bury it in the plane?

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------