Thanks, Daan. I just downloaded the file before you get sued and forced to
removed it again from your site.
Peter
"D.Terstegge"
<[log in to unmask] To: [log in to unmask]
TMFWEB.NL> cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST
Sent by: Aero/ST Group)
TechNet Subject: Re: [TN] 0402 tombstone problem
<[log in to unmask]
ORG>
04/11/02
01:30 AM
Please
respond to
"TechNet
E-Mail
Forum.";
Please
respond to
"D.Terstegge"
Hi Ed,
A good article called "TOMBSTONING OF 0402 AND 0201 COMPONENTS: A STUDY
EXAMINING THE EFFECTS OF VARIOUS PROCESS AND DESIGN PARAMETERS ON
ULTRA-SMALL PASSIVE DEVICES" used to be on the Plexus website.
Seems it disappeared when Plexus changed their website, but I uploaded the
document to my own webspace, where you can still download it at
http://www.smtinfo.net/docs/tombstoning.pdf.
What do you think, am I violating copyrights this way ? (comments welcome,
off-Technet would be best I guess)
Anyway, hope it gives you some clues...
Daan Terstegge
http://www.smtinfo.net
----- Original Message -----
From: Edward S. Wheeler
To: [log in to unmask]
Sent: Tuesday, April 09, 2002 7:59 PM
Subject: [TN] 0402 tombstone problem
Hi folks, we are running a new board with 0402 parts on it. It seems that
we are having a tombstone problem as well as a problem with parts not
staying centered on the pads. We are currently using 20 mil square pads on
the board, with 20 mils of spacing between them. Our stencil is 6 mils
thick, laser cut and electro polished. The trapezoidal walled apertures
are
slightly reduced, 17 mils square, and centered on the pads. It appears the
chip shooter is placing the parts perfectly. We are using eutectic solder
paste with an OA flux, and reflowing the parts using the recommended
profile.
Are there any suggestions any of you might have concerning this size of a
part? Is there a better stencil design, reflow profile, or pad design that
could help us out? I would appreciate any suggestions.
Thanks.
Ed
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