Skip to content

What is NC Drill File?

Generating the NC Drill Files Based on Different Softwares for PCB Design

Printed circuit boards form the backbones of all electronic equipment and devices. There has been a rise in the circuit’s density and the reducing size trends of the electronic products. This has caused circuit boards to transform into a higher complexity.

Vias or holes, which serve as electrical connections forming between the layers and the corresponding functions that a board will use according to the requirements of the design will not work effectively unless you design or manufacture them suitably.

For any unsuitable manufacturing, you can solve it easily. This is by choosing a top PCB manufacturer for unsuitable design. Also, the solution majorly depends on the engineers who have designed the circuit board. They must create a reliable design file with respect to what the fabricators of the PCB does during manufacturing.

It is a general belief that the generation of the NC drill file has been an issue for most engineers of PCB design. This is why it is necessary to summarize the guidelines of the design board on the software for your PCB design.

What is NC Drill File?

NC Drill File is also known as numeric control drill file. This indicates a file that regulates all the information relating to via or hole drilling requirements. These include hole location and size, and tooling size.

It is very necessary for engineers of PCB design to create the NC drill files. This is because you can avoid so much trouble by converting the PCB files into Gerber files or NC drill files.

However, the truth is that some engineers end up sending the PCB files to the PCB manufacturer directly. They fail to convert into Gerber files or NC drill files.

The usual workflow is this. After receiving the files of the PCB design, the board fabricators will have to go ahead and convert them into NC drill files. Then can they continue with the manufacturing. This is because the electronic engineers that work in the PCB fabrication house have a different understanding of PCBs from that of PCB engineers. It is possible that the Gerber file isn’t what the pcb designer was expecting.

Furthermore, during the generation of the Gerber files, some indefinite aspects or issues may result. This is due to differentiations in software version. The best solution is, engineers of the PCB design will have to convert these design files to Gerber files. The NC drill files will also be created, which will all be sent to the PCB manufacturers.

What Does the NC Drill File Format Look Like?

You can generate NC Drill files by using almost all the softwares for PCB design with Excellon as its usual or ordinary format. Excellon was initially a CNC system manufacturer for routers and drillers.

Due to its active role as well as long life in PCB routing and drilling equipment, there is an acceptance and coining of Excellon as some industry standards.

Generating NC Drill File Using Altium Designer

Checking Altium Designer’s main interface, click file, then fabrication outputs, after then, click NC Drill files. Next, go to the dialogue of the NC Drill setup, where you have to specify some options, which include the NC Drill Format, Coordinate positions, Trailing/leading zeros, etc.

Data units in NC Drill Files could be either millimeters or inches, which should work with those of the Gerber files. As regards the format, there are three major sections present. These include 2:5, 2:4, and 2:3. Here 2:3 shows the least resolution. The 2:5 shows the greatest resolution.

Furthermore, before you go ahead to make a decision regarding the format, it is very important to reach out to the contract manufacturer of the printed circuit board in order to ascertain which of the format works with their level of manufacturing.

With zero suppression, the NC Drill files are driven to be neat and fit and it relies on the application, convenience, and hosts of the PCB designers.

When you suppress leading zeros, the starting zeros will end up being removed. So also, when you pick suppress trailing zeros, then the ending zeros will become removed.

There are two alternatives for coordinate positions. These include relative origin and absolute origin. You should choose any of these according to the specific requirement of the pcb designer. However, it has to be exactly the same as the coordinate positions, which are regulated in the Gerber files.

You can pick other items, if they are necessary for the projects. Once all the items have been determined, just press OK. This generates all the NC Drill files that will be stored into the subfolders default path under the folder that contains the project file.

Generating NC Drill File By Using OrCAD (Cadence Allegro)

This is different from the Altium Designer. The NC Drill Files’ default format that Cadence Allegro exports, is not for Excellon. So, before generating the NC Drill Files for real, it is important to set certain parameters. All you have to do is to click Manufacture, then NC, then NC Parameters. This will help you gain entrance into the NC Parameters dialogue.

In this dialogue, there’s a need to determine the items of Excellon format and Output file. Concerning the Code in the Output file, generally, it is acceptable to pick the ASCII. This is because it is a much newer code type in contrast to EIA.

In order to create an NC Drill File using Excellon’s format, it is important that you click before the Enhanced format of Excellon. To achieve zero suppression, make sure that you click before Trailing or Leading zero suppression with respect to the demands or project needs of the PCB designer or just to conform to the Gerber Files.

Furthermore, after the determination of the items, click the Close button. This will allow the NC Parameters dialogue to escape. After determining the items present in the dialogue, tap Drill. This will end up the generation of the Drill Files generation.


In this article, we have been able to explain ways of generating the NC Drill Files based on different softwares for PCB design. Please message us if you have any questions.