This post is part one of a multiple part blog on Making Printed Circuit Boards on a CNC Mill.
Before we get into making a PCB on a mill we need to understand PCBs and why they came to be. PCB is just an acronym for printed circuit board. A PCB is a base for physically supporting and wiring the surface mounted and socketed components in most electronics. These boards work by having small paths that are inlaid into the board, carry electricity between mounted components on the board. Components are mounted with solder, which is a metal that conducts electricity, as well as hold components to the board.
Before PCBs, one could make a board using the old method of point to point wiring. This method created functionally effective boards, but was tedious, time-consuming, and created disorganized, unappealing boards. The benefit was that you could create these boards at home if you possessed the proper knowledge, skill, and materials. This method is similar to a PCB in that it uses solder to mount components. Where their difference lies is in the wiring. The wires on a PTP board are connected via solder from point to point. On a PCB, a thin copper film is laid on a silicone board in the desired wiring configuration. Then the board is coated with a clear epoxy, sealing the copper film into the board. From there, holes are drilled and components are soldered on. You can probably tell based on the pictures as well as the process, PCBs take a little more precision and special equipment to manufacture in comparison to PTP boards. PTP boards are ideal for prototyping before going into production of a PCB, but they do have their downfalls, mainly time-consuming and appearance. With the use of a CNC mill, a faster and more attractive prototyping can be done to create PCBs.
Milling a PCB is a quick way to prototype a board, ensuring all the correct components function properly as well as simplifies the process if any changes need to be made. Milling a PCB is an easier process than wiring a PTP board. The first step in using software like Fritzing to design a board. Once a board is designed the line file is exported to Solidworks
so VisualCAM can generate G-code for a mill to follow a tool path. Once this is all accomplished a blank PCB board is inserted into the mill. The mill executes the code, cutting grooves to act as the wires as well as holes to solder on components.
In my upcoming posts, I will walk through how we take a board from the design process to turning it into a manufactured PCB.