Making or manufacturing a circuit board involves several complex processes.
Photoengraving: Under this process a mask or photomask is combined with chemical etching to subtract the copper areas from the circuit board substrate. The photomask is created with a photo plotter design using a CAD PCB software program. Photomasks are also created using a laser printer.
Lamination: Multi-layer printed circuit boards are made up of multiple layers consisting of several thin etched boards or trace layers and are bonded together through the process of lamination.
Drilling: Each layer of the printed circuit board requires the ability of one layer to connect to another; this is achieved through drilling small holes called “VIAS”. Drilling is mostly done with the use of an automated computer-driven drilling machine.
Solder plating: Pads and lands where electronic components are to be soldered on the circuit board are plated to allow soldering of electronic components. Bare copper is not easily solderable. It requires the surface to be plated with a material that facilitates soldering. Earlier lead based tin was used to plate the surfaces, but with RoHS (Restriction of Hazardous Substances) compliance enacted newer lead-free materials such as nickel and gold are now used for plating.
Testing the circuit board: Prior to assembly of electronic components on to the board, it needs to be tested. This testing can be done using nails tester, flying probe tester are other computer-operated circuit board testing equipments.
PCB Design Rules
Layer Process Vs Standard Size
Minimum trace / space: 7 mils
Minimum via / hole size: 14 mils
Minimum pad for plated hole / vias: 26 mils
Minimum plated slot: 32 mils
Minimum solder mask Clearance: 4 mils
Minimum silkscreen Clearance: 4 mils
Minimum silkscreen line width: 6 mils
Minimum board copper/edge margin: 10 mils