Just out of curiosity, what is the rule of thumb for via size for plating vias shut? Does aspect ratio come into play?
Jim Marsico
ITT Corporation
1500 New Horizons Blvd.
North Amityville, NY 11701
631-630-5079
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Thursday, September 01, 2011 7:55 AM
To: [log in to unmask]
Subject: Re: [TN] QFN with solder slug
Hi Mark - our preferred method is to plate them shut so that we have no
possible issues for either solder thieving or some type of process fluids
(either fabrication or assembly) entrapment. The cost of the board
increases but we feel the increase is worth it in terms of issue
avoidance.
Dave
Mark Larson <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
08/31/2011 04:21 PM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Mark Larson <[log in to unmask]>
To
<[log in to unmask]>
cc
Subject
Re: [TN] QFN with solder slug
Thanks, I wanted to hear how others are doing it, only thing different we
are doing is using 10 mil via, and that should be less of a problem than
12, and we are not connecting all layers to the vias, just the back side.
Dave - yes, that is the main point we are now debating, to cap the vias or
not with soldermask. By cap I mean put a layer of soldermask just slightly
bigger than via hole, then the "normal" layer of solder mask, to the
bottom side only of course.
as for filling them, we really want to avoid that.
Perhaps our real problem is being too conservative (small via, we are only
using 5 where the design engineers estimate is 6-8, and not connecting
inner same net planes) will prevent enough heat transfer, the whole point
of the slug, right?
---------------------------------------------------
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
-----------------------------------------------------
This e-mail and any files transmitted with it may be proprietary and are intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the sender.
Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of ITT Corporation. The recipient should check this e-mail and any attachments for the presence of viruses. ITT accepts no liability for any damage caused by any virus transmitted by this e-mail.
______________________________________________________________________
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
-----------------------------------------------------
|
