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Mon, 13 Apr 1998 02:39:10 -0500 |
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JoAnn about the trace widths it is or should I say was true, about price
going up as the trace with and trace spacing went down.
About 2 year ago, A board shop I used to deal with Would charge more for 8/8
width/space as opposed to 12/12 however if you talk to them and ask them
first, it could be possible that they could do 10/10 with no penalty in
price.
You also have to understand that in large volumes, the board fab house would
scrap a lot more boards at 8/8 than at 12/12.
I have talked to a few board shops and it seems that 10/10 is pretty much
the norm.
Now 8/8 it is still a bit higher in price. You might get lucky and find a
board shop that won't charge a premium for that kind of spacing.
Patrick Jabbaz
Halliburton Energy Services
Circuit Board Designer
(281) 596-6697
[log in to unmask]
-----Original Message-----
From: JoAnn Amerson <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Monday, April 13, 1998 1:31 PM
Subject: [DC] Trace width
Once again I turn to you pleading for help. The "powers that be" are
requiring us to use a 12 mil wide trace as a minimum unless we
absolutely cannot because of lack of space. It seems our board
vendors have difficulty meeting a width and trace at 8/8. My pleas
to look into other vendors fall upon deaf ears. "They're too
expensive!", they cry. So we pay the price over-designing our
boards. Our boards are predominantly low current, low voltage. 8
mil usually is more than enough but......I'm sure you've all run into
this argument at one time or another.
What I'd like to hear from everyone are reasons why we *shouldn't*
use a wider trace than necessary - if there are any. Other than it
takes longer to route a board with wider traces. They don't care
about that. What documentation can I offer to them to make our lives
just a tad bit easier? Or am I lost in wishful thinking?
And also, today's dumb question:
I know that spacing between traces is governed by voltage and the
width is governed by current load and temperature rise above ambient.
If I use a 12 mil wide trace, can I still maintain an 8 mil wide
space to the next trace? Assume it meets the spacing for that
voltage. Or is the spacing always at least track width?
I appreciate any and all responses on these issues. :-)
Jo
JoAnn L. Amerson
Design Librarian
Red Lion Controls, Inc.
E-mail: [log in to unmask]
Voice: (717) 767-6961 ext 6308
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