How to Convert ExpressPCB Files to Gerber

The following steps describe converting from the Express PCB file format to other file formats. By reading the files with Copper Connection software, the circuit boards can be easily searched, printed, or exported to Gerber and Excellon. This allows you to order PCBs from the manufacturer of your choice, as well as to migrate your collection of ExpressPCB boards to more advanced programs.

Important Note: ExpressPCB is not affiliated with Robot Room or Copper Connection. The use of their trademark is for descriptive purposes.

Reading ExpressPCB Files

Copper Connection can read files created with ExpressPCB software versions 4.0 to the present. (Version 7.0.2 -- released Oct 3, 2009 is the present ExpressPCB version as of when this article was last updated in January 2015.)

Older ExpressPCB files (circa 2003 or earlier) need to be opened in one of those compatible versions of ExpressPCB, and then saved to update the file format. Be careful not to use a version newer than 7.0.2, in case the file format changes again. Before updating the file format, make a backup of all of your files and retain your ExpressPCB software installer, in case you need it again.

Opening ExpressPCB files for Conversion

To read ExpressPCB files in Copper Connection, first download and install the Copper Connection software. Then, open your Express PCB files in Copper Connection as you would any other file:

Dragging ExpressPCB files for conversion

Dragging ExpressPCB files for conversion

An immediate benefit is that you can see thumbnails of all of your ExpressPCB files and you can even search them!

Preview and search ExpressPCB files

Preview and search ExpressPCB files

Copper Connection does not alter the original ExpressPCB files themselves. The files are simply read into memory.

Double-click on a thumbnail to open the file. Then, if desired, choose Save As from the file menu to save a copy of the file in Copper Connection format.

Inspecting and Adjusting

The automatic conversion process is excellent, but there may be differences. See the Differences section at the end of this article for details.

You must thoroughly inspect the resulting boards and possibly make tweaks. It is important that you perform your full QA (quality assurance) process on converted boards, particularly before placing a large production order.

Copper Connection is more flexible and includes more features than ExpressPCB. So, you may want to take the opportunity to make improvements to the boards:

ExpressPCB file converted to Copper Connection and then improved

ExpressPCB file (left) converted to Copper Connection (right) and then improved with symbol and font changes


Printing an ExpressPCB file for etching at home is much easier in Copper Connection, as it performs the necessary flipping and color conversion automatically. In Copper Connection, choose Print from the File menu and select the choice that is right for you.


Print options

If the first four choices aren't what you need, you can set the output manually. Return to the editor to customize the layer colors / visibility, grid, zoom level, and board orientation (Turn Board Over). Then, choose Print from the File menu and choose "As Displayed".

Export to Gerber and Excellon

The features described so far are available in the Home Edition, which is free of charge. The ability to export and to save as text format are purchased features. See Buy for complete details.

Gerber and Excellon are the industry-standard format accepted by all PCB manufacturers. By exporting to this format, you can use any manufacturer you'd like.

To export ExpressPCB files to Gerber and Excellon:

Export settings

Export settings

Copy and Save as Text Format

Most elements on a circuit board consist of primitive geometric shapes and their coordinates. As such, each element can be described in a line of human-readable text, which can be copied or saved.

Alternatively, save the file in RRPCB format and open it in a text editor.

In either case, the text format of the elements is tab-delimited, also called tab separated values (TSV). There are a number of free utilities to transform tab separated values into comma separated values (CSV), XML, HTML, or JSON. For example, see Mr. Data Converter.

Custom Components

Copper Connection reads custom component files (.p) that were created with the versions of ExpressPCB mentioned earlier. Component files can be displayed in the Gallery and opened like all other files.

Better still, a component file can be dragged onto any open board to place the component wherever you drop it.

Drag custom components into place

Drag custom components into place

This provides a way to continue to use your existing custom components in a list-like fashion, without having to build them into the Copper Connection parts library.

This also provides a convenient way to build up your Copper Connection parts library, in an organized way, at your own pace. For example:

1. Create a new blank board (File->New).

2. Drag each custom ExpressPCB part file of a similar type (such as capacitors), one at a time, to the blank board.

3. Make sure each part has an ID. The ID is located in the Description section of the ribbon. For example, 'C' for capacitor. The ID does not need to be unique -- and usually won't be if you're putting similar parts into the same parts file.

Part ID and part number are required

A part ID letter and a unique part number are required

4. Make sure each part has a part number that is unique (such as "Capacitor 0.1 in or 0.2 in"). The part # is located in the Description section of the ribbon. By default, the part number is filled out with the file name of the part file you dragged over.

5. Choose File->Board Properties and type a category (such as "Capacitor") in the Categories field in the Documentation tab. This organizes them into the correct category in the Parts Library window.

Board Properties window Documentation tab Categories field

Board Properties window Documentation tab Categories field

Parts filtered by category based on the Board Properties of the part file

Parts filtered by category based on the Board Properties of the part file

6. Choose "Save to User-Defined Parts Folder" in the File menu. The file name you choose is not important.

7. Now those parts will be available visually in the Copper Connection Parts Library.

Differences in Converted Files

Below are the currently known differences between ExpressPCB and Copper Connection in reading ExpressPCB files (both boards and components). There may be additional differences -- please contact us if you discover any.

If you don't use planes/pours, thermals, or four layer boards, these subtle differences will not occur for you.

1. Pour Clearance

Rectangular pour clearance around text is a slightly different size and position in Copper Connection, particularly for larger font sizes.

Large 0.2 inch text in filled plane has slightly different keep out

Large 0.2 inch text in filled plane has slightly different keep out between ExpressPCB (middle) and Copper Connection (right)

Additionally, pours may theoretically produce slightly different results, as they are generated by different programs.

These differences are usually small and insignificant. Most hobbyist boards don't use planes. However, if necessary, you can add Keep Out rectangles or polygons to adjust for these differences.

2. Thermal Relief Shape and Thickness

The thickness of the plane connections in thermal reliefs sometimes varies (unintentionally?) in ExpressPCB. It is constant across hole sizes in Copper Connection (set in the Board Properties).

For example, in the picture below, look at the black arcs and the yellow lines. In ExpressPCB, the black arcs don't always touch the yellow lines. That is, for the far left and far right holes, ExpressPCB generated the same thermal relief even though the holes are different sizes, but did not do so for the middle hole.

Middle thermal has different connection thickness inExpressPCB

Left: The middle thermal has different connection thickness in ExpressPCB. Right: The thermal thickness is consistent in Copper Connection.

Regarding inner layers, for some reason ExpressPCB cuts the thermal relief (the gaps) inside the diameter of the pad's annular ring -- at least that's what it displays on the screen. Thus, for large holes, the ring is smaller on the inner layers than it is on the outer layers.

Inner layer ring thickness

Inner layer ring thickness differs in ExpressPCB layers

Copper Connection cuts the thermal relief outside of the diameter pad's annular ring in all layers. This is consistent and always provides the pad size specified, regardless of layer.

3. Inner Layers

ExpressPCB displays square pads as circles (which makes it difficult to determine part orientation) with the minimum pad size on inner layers, whereas Copper Connection retains the user-defined size and shape.

Differences in pads in inner layers

Differences in pads in inner layers