How to Create Manufacturing Files For Personalized Printed Circuit Boards: A PCB Design Guide By Kingtech

This time PCB Kingtech will review the fundamentals of creating manufacturing designs for PCBs and
manufacturing.

If you re working on a PCB layout, you're working on a file specifically designed for your CAD software. It's not a
universal format type, and it contains details that the manufacturer of the PCB doesn't require. This is the reason
you need create a different type of file (with an exception we'll go over in the final section of the article) before
you can transform your virtual layout into a real circuit board.

Guide to Ordering and Assembling Printed Circuit Boards

This piece is part a series

PCB Schematic and Board Layout

How to Generate Manufacturing Files for Custom Printed Circuit Boards

How to Choose a PCB Manufacturer

What Is a Gerber File?

The most commonly used file format used for PCB manufacturing is known as Gerber. If manufacturers request
"Gerbers" or "Gerber files," they're refer to ASCIl files that are formatted in Gerber data. Gerber files are not
designed to be a source of information. Gerber file is not aware of designs guidelines, network connectivity or
component libraries. It is merely two-dimensional art which indicates where the manufacturing equipment will
put the solder mask, copper or silkscreen. A single Gerber file contains the information needed for one PCB
feature that is on one layer. So, if you've got two layers with each side having an solder mask and silkscreen, then
you'll need to have six Gerber files. It is also possible to require an additional Gerber file to mark the outline of
the board. The image below shows the screen of my CAD tool, and the corresponding Gerber files.

The layout is at the top. The images in the bottom depict the Gerber information that correspond to (left left to
left to) the silkscreen on top and the solder mask on top the top copper and the bottom copper. I also included
the outline of the board in every file just to show the board outline). This board is an C2 adapter that I
developed to program and debug Silicon Labs microcontrollers.

Making Gerber files can be a bit complex. It involves a number of parameters, and the different manufacturers
have different specifications. The screen below shows the options available to take into consideration when
creating Gerber files using DipTrace.

If you're not sure if you have any experience with Gerber generation I would suggest following the steps Choose
one that has specific guidelines for creating Gerber files using specific CAD tools. Then, you can use some of
these programs to design your circuit. If you follow the directions with care, you'll definitely avoid the two
possible outcomes of insufficient Gerber files delays in the process of manufacturing (more likely) or a non-
functional PCB (nowadays most likely quite uncommon).

The Drill File

It is also necessary to create a file that shows the location and size of each hole to be drilled into the PCB, i.e.
that includes through holes (for fixing parts) as well as vias. This file is known as"the NC (numeric control) drill
file. You might also find "Excellon drill file" (which originates from Excellon Automation the company that
manufactures equipment for PCB production). It is recommended is to follow the specific instructions from the
manufacturer of PCBs.

ODB++ vs. Gerbers

Geroer files are accepted by all and I would suggest that you spend the time to become familiar with Gerber
generation. You can then gradually develop the Gerber routine that will allow you to swiftly and easily build your
PCB manufacturing documents. In some instances, it is recommended to utilize ODBone or two files. It is true
having to manage multiple Gerber files can be quite a hassle and that's one advantages that comes with using
the ODB++ format: it's a single data arrangement that (in my experiences) can be created without a lot of input
from the creator.

I was able to fabricate a board with ODB files, however I observed some peculiar issues that brought me to
Gerbers. I'm not saying ODB++ isn't problematic in itself however ultimately, it's irrelevant-if my CAD program
isn't able create the files or if the fab house doesn't know how to interpret the format, it's not useful for me. If
you've had consistently good results using ODBand ++ please let us know by leaving a comment in the section. It
would certainly be beneficial if we could slowly move towards a move away from Gerbers and move to an easier
and more robust method of packaging and transfer PCB manufacturing information.

Project Files vs. Manufacturing Files

If you'd like to avoid creating any kind or manufacturing files, then you should find a PCB manufacturer which
accepts your CAD program's project files. I'm assuming that the manufacturer employs some automated method
to generate Gerbers from your project file This is advantageous not only for saving your time, but it also means
that the fab house staff will (presumably) be aware of the best way to create files appropriate for the equipment
they use. The next section contains information about a manufacturer who accepts projects.

In the next article PCB Kingtech cover the selection of a PCB manufacturer who can make your design, and also
the options for assembly.