The fundamental function of a PCB milling machine (printed circuit board machine) is that it selectively mills away a layer of copper on the substrate of circuit board material to develop conductive areas, pads, structures, and traces on the board surface. These specialized machines are also able to form vias.
Hardware- The PCB milling system consists of a single PCB machine that performs all actions that are required to develop a board of prototype with the exceptions of vias insertion and hole plating. These machines need a standard main outlet of AC and a vacuum cleaner (shop-type) for operation.
Software- Software used in PBC milling machines is generally given by the computer numerical control (CNC) machine manufacturer. The packages can be divided into 2 main categories; vector and raster.
The raster calculation using software that creates tool paths have a low resolution process if compared to the software that is vector-based (it depends on the information that the raster provides).
What should a basic PBC milling machine have?
A PCB milling machine in the category of budget-priced ranges around 3000 dollars that has a spindle which runs at a speed of 50000 rpm and it has a small 2.5 microns or less runout. It should list a precision of 4 microns in X and Y. It should also list 1.25 microns only in Z. The maximum rate of feed should be 3800 mm per minute and the machine should include surface track that is said to yield consistent results in a deep cutting.
The mill should come with control software that will take the industry-standard of designs and use them to plot up to 6*4 inches of board features. A machine should create space designs of 4 mil trace or 5 mils with multiple chip surface-mount packages. They should complete a double-sided board containing drilled holes within an hour.
Are PCB milling and Chemical etching similar?
The PCB milling machine uses a subtractive process that is, to develop ground planes and electrical isolation, board material is removed like the process of chemical etching. However, a PCB milling machine follows a non-chemical process (no exposure to toxic and hazardous chemicals) unlike the process of chemical etching. But, high-quality boards of a circuit can be produced by using both the milling and chemical etching process.
The PCB milling machine creates circuit boards whose quality is determined by the true weight control and milling accuracy of the system, as well as the temper and sharpness of the bits and the rotational or feed speeds respectively. Whereas, in chemical etching, the quality of a PCB totally depends on the mask’s quality and accuracy and it protects the copper from the etching chemical’s state and harsh chemicals.
What are the advantages of using a PCB milling machine?
PCB milling machines have the advantages of creating some special designs of PCB and prototyping. The rest advantages are;
- No use of toxic chemicals for PCB production.
- Making in-house prototypes through PCB milling machines will save time in case of PCB outsourcing.
- PCB milling machine does not require drilling and cutting out the board from the material (base) for creating high-resolution PCBs. Whereas, it is required in the wet chemical process.
- If the PCB milling machine contains computer numerical control (CNC) prototyping then, it will yield a faster turnaround in PCB production than wet processing. A computer numerical control machine helps to process milling, cutting, and drilling.
What are the limitations of using a PCB milling machine?
There are certain limitations on the things that can be accomplished with a PCB milling machine. The basic constraint is the fact that only 2 layers of boards is possible on a simple mill. As well as creating a solder mask is problematic too.
The milling machines that produce PCB can be too expensive. The least range of price for these machines is around four thousand dollars and the more sophisticated ones (that can do vias) range around a whopping twenty-five thousand dollars. The laser-based sophisticated machines are available at a six-figure price range. This equipment use laser for removing materials and thus, they have an upper hand if compared to the standard mechanical milling. It includes better precision and no wearing out of drill bits.
I hope you have all your questions regarding PCB milling machines answered. Choose your PCB milling machine wisely.