PCB Milling

PCB Milling is the process of milling away copper from a sheet of printed circuit board material to create traces, pads, and holes according to a digital layout file.

A video illustrating the process

Why PCB milling?

  • PCB etching can be inconvenient
    • Requires hazardous chemicals such as ferric chloride
    • Have to drill holes yourself
    • Quality of the circuit board depends heavily on the quality of the photomasking and the etching chemicals
  • Ordering PCBs online can take a while (2-3 weeks)
  • In comparison, milling is faster, safer, and more convenient
  • CNC milling is also good for:
    • Jewelry
      • Delicate filigree designs
      • Engraving
    • Prototyping
      • Various materials like ABS, modeling wax, and acrylic

Milled PCB

Jewelry

What you need

  • CNC mill
    • Haas Mini Mill (TechSpark has one)
    • Roland iModela
    • CNC-3020 (generic, inexpensive)
    • Sienci Mill One (about 400 USD)
  • Copper-clad board
  • Software
    • Eagle with pcb-gcode plugin
    • Alternatives: gEDA, FlatCAM, many others

Bits

How-To and Tips

  • General instructions
    • Generate your circuit board layout
    • Use the generic gcode style
    • Set the spindle speed in your gcode to around 15,000 RPM
    • Attach the copper-clad board to the milling area with tape or glue
    • Mill
  • See More resources for more detailed instructions
  • Tips
    • Drill holes before milling the traces
      • Prevents pads on the board from being destroyed by the drill bit
    • Auto-level to deal with irregularities in the surface
    • To reduce burrs, use oil and a slower milling speed

Campus Locations and Access

  • Locations on campus
    • Tech Spark MetalShop (Hamerschlag Hall C Level)
      • Haas Mini Mill
      • Haas Office Mill 2
    • IDeATe spaces (Hunt Basement)
    • DFab (Margaret Morrison sub-sub-basement)
    • School of Drama Scene Shop (Purnell 1st Floor)
    • Not sure how suitable the CNC routers and mills on campus are for PCB milling
  • Courses you can take for access
    • 24-200: Machine Shop Practice
    • 24-203: Intro to Manual & CNC Machining

More resources

A guide on Hackaday
RepRap’s in-depth software review and how-to
CMU ArtFab’s guide to milling small PCBs on the Roland iModela
Ayesha Ebrahim’s Tutorial
Someone’s First PCB Milling Success