Customizing Gerber files in today’s fast paced world of race cars, privately owned jets, and electronic engineering can be challenging. What’s a Gerber format file you ask? In addition to being something Gerber Life child insurance keeps around the office, it’s a format for printed circuit board files. It’s sort of the PDF of PCBs. There are lots of software programs that marry schematic capture and circuit board layout. Some are free, others are in the 10s-of-thousands-of-smackaroos. The PCB layout programs create files that convert the screen artwork to a standardized drawing format for circuit board production. Those standardized files are in Gerber format, and there are different types of sub-formats.
Gerber viewers are good for seeing exactly what your circuit board will look like when built. Although it is rare, I have had a circuit board where the PCB layout was different than the Gerber file output, and not in a good way. Using a Gerber viewer to check your design is good practice. While Gerber file viewers are cheap and easy to find, Gerber file editors don’t seem to be on the “free” side of things. Our company has a Gerber file editor, oddly enough called GerbTool, that came with OrCad. Orcad is the software we’re currently using for schematic capture and PCB layout. I’m pulling for a switch to Altium, but like anyone with 10 years of files, change is scary. We’ll pull the trigger on that someday, but not today. So I find myself in need of a Gerber file editor.
Why? During a recent design it was determined that we need to create an array of small circuit boards, and we may need to change the array with each production run. GerbTool and Orcad can be used to create this array as long as none of the reference designators on individual boards match (part numbers like U1, U2, etc). Each board would have to have part numbers different from all the other boards. That would play hell with datasheets and documentation. Not a really good option.
In the past one of our PCB manufacturers recommended GC Prevue as a good (and free) Gerber viewer. That led me to download a demo version of GC Prevue Plus, a product by GraphiCode. They offer a 7 day trial of the full version of the program. That’s not a long time to get a feel for the program, but it did prevent me from putting the project on the back-burner, which I always do when I have a 30-day trial. GC Prevue Plus runs about $500. There are some pretty expensive add-ons associated with design-rule checking, annual support plans, assembly coding, and ODB’ish things that can push the cost into the $4,000 range.
However, looking at our needs, the $495 version should work. And it took me just a couple of hours to import two sets of board files figure out how to offset them, and export them as combined files (might have been quicker if I used their tutorial). Once I figured out how to use GC Prevue Plus that process took about 5 minutes. The image above is a single copper layer (top) that was produced from two Gerber files created by OrCad Layout. I’ve got some more work to do, but I’m hoping to get this board arranged and to a PCB manufacturer (we use Advanced Circuits for prototypes and some production runs). I only have 6 days left in the demo, and I’d like to get some files through the PCB manufacturer’s DFM check before I buy the program.
So far though GC Prevue seems to do the trick. We can even use it to assemble arrays of different prototype boards. Just a half-dozen combined PCB orders would end up paying for the cost of the software.