Being an old timer (first layout in 1983), I have to agree never saw traces between smt pins cause a problem - to avoid tombstoning, more important to have correct pad sizes (1 mil can make the difference) - and with high volume manufacturing (disk drives) we probably would have seen a problem, had there been one.
However, now out of disk drives and pcbs - happily in GPS management!
Cheryl Johnson, CID+
now WW Service Technologies Manager, Trimble Navigation
----- Original Message -----
From: "Mario Irigoyen" <[log in to unmask]>
To: [log in to unmask]
Sent: Thursday, April 30, 2009 4:40:48 PM GMT -07:00 US/Canada Mountain
Subject: Re: [DC] Traces and vias under components
My 2 cents, I've been running traces between pads of 1206's and even
0805's and sot23's since, well, a long time (20+ years), will NO ill
effects.
Mario Irigoyen
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of S.
Roy
Sent: Thursday, April 30, 2009 12:00 PM
To: [log in to unmask]
Subject: Re: [DC] Traces and vias under components
Hello everyone,
Stupid question but...
An Engineer would like to know why it is such a bad idea to run traces
between the pads of the same component, i.e., a 1206 resistor or cap. I
know I shouldn't do it, but I can't put my finger on the spec that
supports
my distain for running these traces. Can someone steer me in the right
direction, please? Thanks...
Respectfully,
Steven D. Roy
PCB Designer
Audio Authority Corp.
2048 Mercer Road
Lexington, KY 40511-1071
(859) 233-4599 X-159
[log in to unmask]
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Andy
Kowalewski
Sent: Wednesday, March 18, 2009 6:21 PM
To: [log in to unmask]
Subject: Re: Traces and vias under components
You can almost guarantee that the board they had trouble with had open
vias
under the components, and wave soldering filled the vias and made a
little
dome on the top side, ready to make short circuits to any metal bodies.
Properly tenting thye vias would fix that problem.
Cheers...
Andy Kowalewski
0424 432 235
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
wheels
Sent: 2009 03 19 01:44
To: [log in to unmask]
Subject: [DC] Traces and vias under components
Guys,
We have a customer which we are designing a mostly SMT board for that
requires all traces and vias not to be under components. This would also
include any planes being under the components. I guess in the past they
had
a board designed by some else that had a shorting problem with traced
and
vias under the components. They are insistence that this is the way it
has
to
be. Has anyone else had experience with this sort of demands? This is
not
for
space, military, high voltage, high vibration or a medical application.
Can
anyone think of anything we could tell they to change their mind?
Thank you,
wheels
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