[sdiy] PCB service firms?

[Barry Klein]

Where I was coming from is that some of these cheap firms seem to want you
to use their schematic capture, then layout, software.  Say I use Orcad, I
then would have to import that schematic in DXF or something I imagine.
Then if board changes are to be made you do them in their schematic software
and the netlist to layout phase is quicker.  The cheap firms do not seem to
push just taking your Gerber files - don't they want to lock you in to them
because you have to use their software?

So say you do not want to be locked into their software - and you must then
go to someone else that doesn't have that restriction.  Orcad can output the
schematic to any of several layout package formats.  You then buy a layout
package and create the Gerber files.  What I heard in the past is that there
is a standard panel size and it is smart to ask what that is so you can fit
as many of your boards on it per panel cost as possible.  So that gets you a
cheap board cost.... but I know nothing about what an pcb assembly house is
looking for - the same panel size or individual boards?  Paul, you were
making your own boards for awhile there and then looking for someone else
to.  What tips may you have discovered to reduce cost in this assembly
phase?

Barry


-----Original Message-----
From: Paul Schreiber [mailto:synth1 at airmail.net] 
Sent: Thursday, September 08, 2005 10:10 AM
To: Barry Klein; synth-diy
Subject: Re: [sdiy] PCB service firms?

Schematics are *no good* for a pcb layout tool except to generate the
connection 
netlist.

If you want to lay out pc boards, you have to get a pcb program. The
universal 
output
are 2 sets of files: the 'Gerber' files used for the traces/solder 
mask/silkscreen and the 'Drill file'
which is 99% of the time in what is called 'Excellon' format.

Gerber and Excellon are companies (both been around 40 years) that make pcb 
fabrication
machinery. These files a very simple ASCII text files.

In today's world, there is no 'extra charges' for SMT. 8mil lines with 8mil 
spaces is considered 'low tech'
nowadays (4mil/4mil is "high tech"). Analog boards with 12+mil lines is "a
joke" 
to fab houses.

Paul S.