Should You Outsource Your PCB Design?
It's an Art
It's not uncommon to outsource the design of a PCB. Designing good, quality PCBs is as much an art as science. I've yet to see any sort of automatic process do as good a job as a talented PCB designer (which is why it can be costly). What though should you be asking for from your PCB designer?
First some terminology. When a designer (or your factory) talks about Gerber files, they are referring to the output of the design process, not the design itself. If you have some desktop publishing background, think of it as the Postscript or PDF files you send to the printer vs the actual InDesign or Publisher files. Often I'll be asked if I can modify the Gerber files to make a change and while possible, it's incredibly tedious and error prone.
The other terms you should know are ERC and DRC. This stands for Electrical Rule Check and Design Rule Check. Most PCB layout programs have some sort of checking mechanism to make sure that everything is connected as it should be and that the PCB layout passes checks for manufacturability and reliability.
The final term is routing. This where once the components have been placed on the PCB layout, the designer routes all of the connecting traces. This is really where the art of PCB design comes out. It's like working on a puzzle in 2 to 4 or more dimensions.
So what should you be asking for?
First, make sure they use a commercial PCB layout program. Autodesk Eagle and Altium are the big players. KiCad, an open source tools is also good. Since you'll be asking for them to deliver to you the design files and all libraries that were used, you want to make sure what they give you is portable to another designer. These are your company assets after all. Second, you should insist that the design passes all ERC & DRC checks and ask for a copy of the report (or screen shot). Third, ask for a 3D model of the complete PCB. All of the major layout programs will create 3D models and you'll find it incredibly helpful to verify that the PCB and the enclosure match up properly. You should specify how much detail you need as well since it can be time consuming making the model.
What should you be giving them?
They should receive from you an outline of the PCB in accurate dimension. This is most easily accomplished by having your industrial designer/mechanical engineer provide a DXF file. Mounting holes and keep out zones (areas where no components should be placed) need to be indicated. If there's specific places where connectors or switches or indicators need to be placed, it should also be called out. Don't forget about antennas and areas that need special treatment. Form should follow function, so don't let the PCB design drive the enclosure where possible, let the enclosure design drive the PCB. If you are unsure if everything will fit, you can give the designer a preliminary envelope and they can do a sample placement before routing anything.
Final piece of advice. Make sure whomever is doing the PCB layout, has electronic engineering experience. In the old days when we laid out PCBs on a light table with acetate and sticky tape, it was a draftsman's job. Nowadays, the person doing the layout should understand how the design works and its intended purpose.
~ Scott Shwarts
