Phil, if you have SMT, you need fiducials.  I don't know whether you're
building in house or using a CM, but what you want to do is check out
what the equipment manufacturer recommends for both your screen printer
and placement gear.  If you're using a CM, they often have a DFM
document that will contain all that stuff.  We put ours in the scrap
rails unless it's a single up circuit, and then they need to be on board
along with tooling holes.  Also, there are some device packages which
require their own fiducials adjacent to the component, so your designer
needs to check for those too.  


Bob Croslin
Nielsen Media Research

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Thursday, May 11, 2006 10:18 AM
To: [log in to unmask]
Subject: [TN] Use of Fiducials & thermal stitching

My disclaimer... I'm a neophyte at SMT and need some education.
 
Fiducials;
At what point do I need fiducials on my boards?
 
Is there a specific pitch or device size that will require fiducials?
 
Is there a "Cliff's Notes" for this?
 
Thermal Stitching;
We have an SMT power transistor that has about 16 thermal stitch holes
located directly under the device.  The adjacent pad area is taken up by
heat sink.  Is this "industry standard"?
 
Short of reading all the IPC standards... zzzzzzzz... oh sorry, I dozed
off there, is there a good source for coming up to speed on SMT and
board layout good standards?
 
Thanks in advance,
 
Phil Nutting

---------------------------------------------------
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
-----------------------------------------------------