PCB programs and etching companies?

[Tony Clark]

> 1)  what program(s) have diy users found to be helpful for creating the
> pcb layouts?

   Listen to the other guys on the list.  I use a $10K packaged called 
OrCAD.  I think there are some other guys that use higher end packages in 
the 40K range (great to be able to use tools at work!).  But unless you 
have access, there are a number of free or near-free tools which are about 
your only option unless you want to shell out a fairly good sized chunk 
of change.

> 2)  what company do you send your pcb's to?  what's the timeframe for
> turnaround, the file format needed (do they handle online submissions?)
> and the $$$?

   I use Alberta Printed Circuits (www.apcircuits.com) out of Canada.  
Been extremely happy with their prices and turnaround times.  A batch of 
10 boards double sided thru-hole plated (no soldermask) and tin-reflowed 
with guaranteed trace width down to 8 mils(!) will set you back around 
$100 USD, including same day processing (if you get it in in time, next 
day if not) and 2-day FedEX shipping.  I find it extremely fast and 
reliable.
   There are some rules that you'll always have to follow in order to get 
the great rates though.  You'll most likely have to restrain your board 
size (which shouldn't be a problem unless your Jim Patchall ;) ), and 
you'll have to stick to a set of standard drill sizes.
   You CAN have odd shapes, but you won't get them routed out.  You'll 
have to do that stuff yourself.  Easily accomplished with a good band or 
scroll saw.

   PCB Files usually go something like this:

   Top layer GERBER file.
   Bottom layer GERBER file.
   Aperture List.
   Drill Tape Summary
   "Excellon" drill file.

   The GERBER files are what actually contains your PCB foil pattern.  
There are a number of different "formats" that GERBER files can have and 
you should find out from the PCB house you choose what format they like.
   For instance, there are two basic flavors of GERBER:  Generic and 
Extended.  Some of the options that you might find in a GERBER format are 
things like:  2.3, 2.4, 2.5, 3.2, 3.3, or 3.4 coordinate format; leading 
or trailing zero suppression; including G-commands; various character 
sets; plus some other things, such as metric coordinates, included 
netlists, etc.

   The aperture list is a list of the various "pens" used to draw your PCB 
foil pattern.  This list must go along with your GERBER file since the 
GERBER file references the arpeture list codes.  The list will include a 
unique code for each "pen" and the size that the "pen" should be.

   The drill file is the file used by the CNC drilling machines to drill 
all of the holes on your PCB.  The most common format is "Excellon" 
(which is a company that specializes in drilling machines, BTW).  There 
are some other formats, but they are probably archaic at this point.  The 
drill file will contain a drill code and a list of coordinates.

   And finally, the drill tape summary file is where the drill codes used 
in the drill file are normally kept (similar to the aperture list).  
Typically you will have to edit this file to change the drill sizes to 
use a PCB house's standard sized drills (or "free drills" as they are 
sometimes referred to).

   Hopefully that will explain some of the details about PCB files!

   Tony

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