Create Your Own PCB Printed Circuit Board Using CNC Milling

Electrical engineers and technicians often use breadboards for prototyping and testing circuit designs. A breadboard is usually a plastic board with a spring-loaded grid of receiving holes for plugging in wires and components. While breadboards are great for quick analog circuit layout, they have several disadvantages. They're large, so easily don't fit into a mechanical enclosure. They can get messy, which makes it difficult to track down defects on complex layouts. Since they are not welded, they are not very strong either.

For these reasons, designers often rush to manufacture printed circuit boards (PCBs) early in the design process. A PCB is a flat plate with wires on its surface that are used to electrically connect electronic components and components.

Unfortunately, between tooling costs, high prices for low volumes, slow turnaround times and limitations in redesign flexibility, small manufacturing runs for PCBs can be prohibitive. As a result, some designers have started milling their own PCBs using in-house engraving CNC machines.

Since CAD modeling is an important step in product design, creating models as early as possible is a good practice in product development. Next, these models need to be converted into CNC programming language G-code using CAD/CAM conversion software. Once the G-code is generated, you can mill the board.

Drill, grind, cut: There are three processes to create a PCB. Drill the first via (component hole). Second, the clearance of the milling marks. Finally, the board is cut to shape.

Tools: Appropriate tools should be used for each process. Drilling drills; end mills for tracking gaps, with square or V-shaped tips; and shaping end mills.

Machine performance: There is a wide variety of small CNC machines on the market with significant differences in the built-in quality. Some are pre-assembled, while others require field assembly. The stiffness and build quality of a machine will determine how accurately and precisely it grinds. A lower quality machine doesn't necessarily mean it can't be used for prototyping PCBs, it just means you may need to consider larger trace gaps, use deeper cuts or use larger tools.

PCB Material: A circuit board consists of layers of copper bonded to a composite substrate, which is usually made of flame retardant materials. FR-4 is one of the most popular substrates in use today. It is a fiberglass epoxy resin. The glass filler makes the material highly abrasive, which will cause rapid tool wear. Precautions should also be taken to avoid inhalation of FR-4 dust that is harmful to human health.

Finishing: The copper layer is prone to oxidation, which can degrade its electrical properties. So once your PCB is milled and the components are soldered in place, it's important to coat the copper. Fortunately, a quick application of nail polish can solve this problem.

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