Electronic Contract Manufacturing

Electronic Contract Manufacturing: The Gerber File Checklist

In the case of an electronic contract manufacturing provider, it is necessary to provide proper Gerber files. They are files with all the information required to form your printed circuit board (PCB), copper traces included to drill holes. Even one error can make the process of production more complex, more expensive, or lead to an unsuccessful board. This checklist is meant to help you make sure that your Gerber files are ready to be sent and before you hit send, make sure you have everything in them.

What are Gerber files?

The standard format of passing PCB design data to the manufacturers is the Gerber files. Your board has a lot of layers or aspects, which are represented as each file. Their combination gives a full blueprint of production.

The majority of PCB design software may produce Gerber files, but this is dependent on how well you have prepared your design.

The Gerber file checklist (Before you send them to electronic contract manufacturing provider)

Have all the required layers

Your manufacturer would require a full set of files to make your board. At minimum, this includes:

  • Top and bottom copper layers
  • Solder mask (top and bottom)
  • Silkscreen (top and bottom)
  • Paste mask (when surface mount components are used)
  • Drill holes (plated holes and non-plated holes).
  • Board outline

When you design a multilayer board, then it can be provided with all internal copper layers.

Check your drill file format

Drill files are commonly made separately of Gerber files, usually in Excellon form. Be sure your drill file has:

  • Tool sizes for all holes
  • Location of holes.
  • Plated and non-plated hole designating.

Make sure that your drill file corresponds with the holes in your copper layers. One of the errors of the highest frequency is misaligned or missing drill data.

Check your board outline

Your PCB board outline determines the size of your PCB shape. It should be:

  • A closed loop with no gaps
    • On a specialized layer (usually referred to as board outline, or mechanical layer)
    • Devoid of repetitive lines or images.

When you have cutouts, slots or other non-rectangular shapes in your design, make sure that they are well defined and are what you intended to have in the design.

Review silkscreen clarity

Silkscreen graphics and text assist in assembly and identification although they should be readable. Check that:

  • The text is readable (0.05 inch or more is suggested to use)
  • Component reference designators are readable and in the right positions.
  • Silkscreen does not overlap vias or pads.

Other manufacturers will not leave silkscreen, which can cause confusion in the assembly process because it interferes with pads.

Set solder mask

The solder mask secures your copper traces and excludes solder bridges in construction. Verify that:

  • Solder mask masks line up with your pads.
  • Pad and vias have sufficient clearance.
  • You have indicated the right color of the solder mask (where necessary)

When you are working with a non-standard solder mask expansion, record this in your fabrication notes.

Use the correct file format

In the vast majority of manufacturers, Gerber X2 or RS-274X formats are accepted. The old format such as RS-274D where additional aperture files are needed should be avoided. In any case, consult your manufacturer on which format they would like.

Included readme or fabrication drawing

Do not think that your manufacturer is going to read your files in the right way. Included with it should be a readme file or fabrication drawing which specifies:

  • Number of layers
  • Board thickness
  • Copper weight
  • Surface finish
  • Special requirements (e.g., controlled impedance, blind vias)

Clarity in documentation also minimizes chances of mistakes and also shortens the quoting time.

Run a design rule check (DRC)

DRC Before you export your Gerber files, run a DRC in your PCB design software. This will intercept such frequent problems as:

  • Traces that are too thin
  • Spacing an insufficient distance between traces.
  • Unconnected nets
  • Overlapping components

Solving these problems during the pre-export phase will save time and prevent the need to make expensive changes.

Preview your files

Check your files using a free Gerber viewer before transferring them. Look for:

  • Missing layers
  • Incorrect layer alignment
  • Other unforeseen forms or objects
  • Proper board dimensions

A variety of manufacturers provide Gerber on-line and in-store Gerber viewers to their quoting service. Use these tools to the best of your ability in order to prevent errors.

Last minute verification of submission

After filling your checklist, feel free to check the whole package of your files. Confirm that:

  • Each file has a well defined naming (e.g. ProjectName TopCopper.gbr).
  • The files are condensed into one ZIP file.
  • Contact and details of your project are provided.

When your submission is arranged well it is easy to have your manufacturer process your order fast and correctly.

Conclusion

One of the simplest means of a smooth electronic contract manufacturing process is submitting of clean and complete Gerber files. Using this checklist, you will eliminate mistakes, prevent wastage of time, and build your PCB once.

You can save several minutes, go over your files once again – it is worth it.

Enjoyed this post? Share it!