Overview

There are several reasons one may wish to convert a Gerber photoplot file back to GDSII. For example, you may wish to use IC lithography equipment to create a photomask -- such equipment generally requires CAD data in GDSII Format. Or you may wish to take advantage of tools such as XOR comparison that is commonly available for IC masks. This app note explains how to use Artwork's gbr2gds engine from a command line (bypassing the user GUI).

RS274D vs RS274X

There are two types of Gerber files we must deal with: the original RS274D file format which goes back 30 years and the newer RS274X format which contains all required plotting information embedded into the file header. Since GBR2GDS was written back before RS274X was popular, it does not read the newer format directly. Instead one has to run a utility that will create job and apt files for the converter.

RS274X

Before converting an RS274X file to GDSII we must run the utility called rs274xjb on it which will produce two resource files needed by the converter.

the command line syntax is:

      rs274xjb  <gerber_files> -job jobfile   -apt aptfile

 where

     rs274xjb           274X scan utility

     gerber_files       a file or files (if more than one use  
                        a wildcard specification) to be scanned.

     -job jobfile       name of the .job file to be produced

     -apt aptfile       name of the .apt file to be produced

Contents of the Job and Apt File

We ran the utility on a simple one layer Gerber file called TOP24.gbr

  rs274xjb TOP24.gbr -job reverse.job -apt reverse.apt

%IPPOS*%
%FSTAX33Y33*%
%MOMM*%
%ADD10C,0.000*%
%ADD11C,0.000*%
%LNTOP24*%
%LPD*%
G36*
X004642Y000305D02*
X004745D01*

:Ver   100
:Cfg   reverse.apt
:Drw   TOP24.gbr
:Lay   TOP24_LPDP1
:OnOff on
:EOL

MACFILE rs274mac.0
CIRANG  90
SUPPRESS TRAILING
ABSOLUTE on
FORMAT 3.3
APTUNITS mm
D10 0.000 d Round 0.000 0
D11 0.000 d Round 0.000 0