Quoting PCB design
It should be noted that this quote form is only for quoting PCB design, or PCB layout, not
product development, overall electronics project design,
schematic capture
or manufacturing. If you need a quote for any of these, please
contact us.
If you get stuck on how to estimate any of these three quantities, but have a
netlist generated from your schematic, send the netlist as an attachment to an
email and we will quote from that.
-
"Component lead count"
(or "
Pin Count
," it's name from pre-SMT days) is a count of all of the
component leads (or pins), whether connected to nets or not and including
mounting hardware, as estimated from the schematic hard copy or bill of
materials. This is the best, simplest method of estimating the size and scope of
the printed circuit design job. If you have only a hand-sketch for a
schematic, then this is the only method that makes sense for this simple quote
form. If you have no schematic yet, then a ball-park quote on
component lead count
is still your best method.
However, a
component lead count
can take some time for a very large schematic
(unless you
use Protel and would download and learn Arachnophilia).
. Most CAE software is not set
up to generate a
component lead count
automatically. But they can usually generate one
of the following data, which we can quote from:
-
"Node Count" or
"Connected Pin Count"
A node is a pin or lead which will have at least one
wire
connected to it. To get a node count automatically, extract the netlist in
Pads-PCB ASCII format
and then literally count the dots (periods, ".") in the *NETS* section. An equivalent alternative is to extract a Protel- or Tango-format netlist and count the hyphens ("-"). I use my
text editor to count
these for me. I select the *NETS* section, and have the editor automatically
count the periods or hyphens in
the selection.
1 Arachnophilia
-
"Connection Count",
"Pin Pair Count"
or
"From-To Count"
Many schematic capture programs will automatically extract a report that gives
connection
count
as a statistic for each sheet. To obtain this number, one would generate a
statistic report and then add up the
connection counts
from each sheet's section of the report. Please note that the following is a true statement:
By definition,
[node count] = [connection count] + [net count]
We need the X- and Y-Dimensions to obtain an aspect ratio and area for estimating density. If this is not
determined, give us the maximum dimensions which you can easily tolerate. If
the board has an irregular shape, do your best in giving us a simplified
rectangular equivalent in shape and area of the sum total of portions of the board available for component placement. If you have no idea yet, then allow
yourself enough room by adding up the sum total of the rectangular area taken
up by each component (including its leads, and you'll need the component "spec sheets" for this) and doubling that. This will give
you enough room for the components and routes without having to go to over four
layers (except for
BGA
designs) and without needing to put components on both sides of the board.
1 Arachnophilia
I use the freeware, actually "CareWare",
Arachnophilia 4.0 for Windows
for counting specific characters in a selection. That's the same HTML editor
used to
design this web site and is a very useful all-purpose text editor. I use the
old Windows version, instead of the new 5.0 Java version, because the new
version
no longer has this feature of counting a particular character within a
selection.
Protel can be used with Arachnophilia
to get a pin count.
When you create the Pads-ASCII netlist, have Protel include "one-pin unnamed nets." Thus, the "netlist" for counting pins includes the nodes of unconnected pins, giving you a pin count when you do this: Select the *NETS* section, and have the editor automatically count the periods in the selection. This won't include any mounting hardware or mounting holes of connectors which are not specifically included in the schematic's symbols, so you would add those in to get the total correct component lead count.
John W. Childers
Open quote form in a new window.
Golden Gate Graphics, Centennial, Colorado 80122-3422, USA
Located in the middle, near Littleton, Highlands Ranch and Englewood, of the Rocky Mountain Front
Range High Tech Corridor, which includes the following cities from south to north: Colorado
Springs, Monument, Littleton, Denver, Boulder, Niwot, Longmont, Loveland, Ft. Collins and Greeley.
© 1999-2005 John W. Childers. All Rights
Reserved. Last update: Thursday, January 31, 2008