Common Errors in 2 Layer Printed Circuit Board Files

Good files lead to good boards which in turn means your ideas become real faster!

These are some examples of errors that we see and that can create delay:

• Missing layers in provided Gerber data.
• Overlapping/buried drills.
• ExtraMissing Solder Resist pads.
• Rare un-terminated traces (prototype hobbyist’s).

 Missing layers:

Sometimes files are missing from the Gerber data provided. We have also found that the file is provided but there is no data contained within the file. Missing files and data can delay the manufacture and subsequent delivery date.

Overlapping Drills:

We have found that overlapping can cause serious problems during manufacture. This can cause the drill to break during the drilling stage with the loss of that section of the manufactures panel. This can lead to the design having to be returned to the customer for an updated layout. This will also cause delays in receiving the finished product.

Drill Format:

This is one error we see on a regular basis, no drill format provided inwith the drill file. This can take some time to work out which format has been used, as not all designerssoftware’s use the same format. An example of a standard drill format for Eagle software 3:3 Decimal, Absolute, MM. Most software provides the drill format with in the header info or in an output file.

Solder Resist Pads:

Some of the problems noticed with the solder resist layers are missing pads and extra pads. The missing pads are just design errors. Some customers use the same components in different layouts and import the solder resist for the component. Due to the different layouts extra pads may be placed in the layout which can cause exposed traces, plains etc. This may cause problems when the pcbs are received by the customer.

Layer Stack Specifications:

It is important to have a layer stack provided with the Gerber data to ensure that the correct layers are used. Some software will output the Gerber layers with extensions like .GTL or .GTS. The .GTL extension stands for Gerber Top Layer and .GTS as Gerber Top Stop (Top Solder Resist).  The outline should be indicated in the layer stack, as some software’s designers use mechanical layers for the outline. Some designers use the .GKO layer which is not advisable and may lead to the wrong size of the PCB. The mechanical layers are also used by some customers to provide manufacturers specifications such as finish, ul-logo, silk screen etc.

It’s always advisable to include a text file with any information you think could help.

Remember ambiguities cause at best delays and at worse issues with the PCB when it’s too late to fix.  In PCB manufacture there is no such thing as TMI (too much information)!