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Re: [Homebrew_PCBs] Re: Suggestions for a simple c.a.d. program

2011-02-17 by Charles R. Patton

I like FreePCB  (www.freepcb.com).  I do boards sporadically (months 
apart) so the program is simple enough to pick up again after long 
periods of absence.  There are NO cripples. 
 From their blurb on the web site:

    * 1 to 16 copper layers
    * Board size up to 60 inches by 60 inches
    * Uses English or metric units (i.e. mils or mm) for most functions.
    * Footprint libraries courtesy of Ivex Design International, PCB
      Matrix and the IPC.
    * Copper fill areas
    * Footprint Wizard and Footprint Editor for creating or modifying
      footprints
    * Imports and exports PADS-PCB netlists
    * Exports extended Gerber files (RS274X) and Excellon drill files
    * Design rule checker
    * Autosave

Pre-viewing the Gerber files
A) After generating the Gerber files, I check them with the free version 
of GC-Prevue.
 (http://www.graphicode.com/Download_GC-Prevue_and_Free_Trials).  From 
this program I laser print (HP4Si) on  glossy paper pages from 
magazines. (Thanks ever so much to the Homebrew list for this tip.  It 
works better than any of the many photo glossy paper I ever tried.) 
B)  I just became aware of another program, ViewMate with "smart DFM" 
(http://www.pentalogix.com/)   that appears to be just as capable -- but 
I haven't tested it through the whole process of printing. 
C) There are also other Gerber viewers that I haven't tried
   http://www.designspark.com/knowledge/gc-prevue-gerber-viewer
   http://www.everythingpcb.com/p17596.htm

Generating the netlist:
A) I generate  netlists from a very old copy of ORCAD. 
B) I have briefly tested Suigyodo Schematic 
(http://www.suigyodo.com/online/e/index.htm) and it seems to work fine 
and is capable of generating compatible netlists including footprint 
names to be included in the netlist. 
C) Another route is to use LTspice  from Linear Technology.  This one 
exports a netlist that requires some minor editing to make it really 
useful as LTspice does not have a "package" field so the case sizes to 
select the footprint are not included in the netlist. 


Additional pluses:
FreePCB  is a very capable PCB editor and data save files are ASCII.  
This is very handy as I have taken NC files from a client, and imported 
them to the board outline with only minor editing to yield a very 
complex board with multiple curved edges and holes that have to be 
placed exactly.  Because FreePCB only does 90 degree arcs in the board 
outline, the NC file is made of a lot of small straight line segments 
(typically about 10 mills). Works for me. 

I have no vested interest in any of the companies mentioned above, other 
than appreciating very much the time people have spent developing fine 
freeware software packages other than ORCAD that was purchased before I 
retired.   (And as a side note, FreePCB is much more stable than the 
early PCB layout packages ORCAD sold for bunches of money -- so paying 
for a commercial product doesn't always guarantee better performance.)

Regards,
Charles R. Patton

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