PCB Milling
PCB milling involves the precise removal of copper layers from a substrate (FR4) to create intricate circuit patterns. Unlike traditional methods like etching, PCB milling is specifically meant for rapid prototyping as it's easy and fast to create a single PCB. The process utilizes a milling machine equipped with a rotating cutting tool to carve out the desired circuitry.
It empowers electronics enthusiasts and professionals alike to bring their innovative ideas to life, fostering creativity and experimentation in the realm of electronics. As technology advances, PCB milling continues to be a valuable tool for those seeking a balance between precision, customization, and cost-effectiveness in electronic prototyping and production.
- Make sure your PCB design conforms to the design rules listed below.
- Next, export your design as Gerber files. Specifically for KiCAD we've added the procedure below.
- Currently we provide one PCB mill, check out how to work with it here: LPKF ProtoMat S63
Design rules
Due to the way the LPKF ProtoMat S63 works, there are some design rules that you need to adhere to. We've listed the most important ones here. If in any doubt, please ask!
- The milling machine can do double-sided PCBs. But single-sided is much easier. So place your components properly and try to trace it with as little bridging as possible. It's a puzzle that requires time and effort.
- The minimum track size is 10 mil (0,25mm). It is not advisable to go any smaller. The machine can do it, but it requires sharp tools. Usually it's not needed to go smaller than 10 mil (0.25mm).
- In milled PCBs, vias are not conductive! There’s no way to plate them other than inserting via inserts. This requires vias to be 0.7mm diameter, with at least 1.2mm diameter pads. Use as little vias as possible.
- Vias cannot go underneath flat packages as the via inserts have a certain height. So design your vias to be outside of any components.
- Holes for through-hole components are not conductive between top and bottom layer. Usually you can’t solder through-hole components on the top side (you only solder the bottom side), so you’ll have to take this into account during design of your PCB. Use vias instead.
- Make sure to use polygon fills on both top side as well as bottom side. It's good practice to connect them to GND.
- Maximum size of you PCB is less than 229x305mm. This is the size of the base material, but the mill head requires spacing between the head and the bolt that keep the base material in place.
- Large PCBs take a lot of time and use a lot of tool lifetime. Be mindful with materials and make your PCB as small as possible.
Gerber files
Milling a PCB requires a digital design of the PCB. This is generally made in PCB design software like KiCAD, EasyEDA, Altium, Autodesk Fusion and others. We advice to use KiCAD because it's a fully featured design software that is open source and well supported by manufacturers of electronic components.
Our milling machine is controlled using a software tool called LPKF CircuitPro. To get your design into CircuitPro you'll need to export the various layers into Gerber files. This is the de facto standard file format used by the PCB industry.
To export your layers in KiCAD, go to File
- Fabrication Outputs
- Gerbers (.gbr)

Select the layers you whish to export. Make sure to at least one copper layer (front copper: F.Cu and/or bottom copper: B.Cu) and the PCB outline (Edge.Cuts).
Make sure to check the options as per this screenshot (especially make sure to use extended X2 format).

If your PCB contains drill holes, make sure to generate a drill file too. Click the Generate Drill Files
button and check the options as per this screenshot (especially make sure to use Gerber X2 as file format).
