Initially a circuit schematic diagram is typically created using CAD software, a Gerber data file is then created which is converted using computer aided manufacturing (CAM) software to form the basic Printed Circuit Board layout. CAM software generates the artwork which is printed using a plotter, this artwork is used later in the PCB manufacturing process. So this means if you are looking for some suppliers to do pcb for you, a Gerber file or PCB file is needed.
PCB materials such as FR4, Aluminum and Polymeric come in various sizes. These are pre-cut into specific sizes. The dimensions depend on the amount of boards required and the layout of the circuit on them. So this means the more quantity you need, the cheaper it will be for the laminate unit price.
First the panels are coated using a light sensitive film, and the images from the artwork are then printed on these coated panels. The printing is acid resistant and thus allows the unwanted areas of the copper panel to be etched away, leaving only the parts forming the circuit.
The etched layers are then laminated together. They are pressed together with thin sheets of resin coated fiberglass at high pressure and high temperature. As the board cools the layers bond together.
The next stage involves drilling holes. These holes are positioned using the drill data from the Gerber data file. A solder mask is then applied as a coating to protect the circuit from any solder splashes applied during the final PCB assembly process. Naturally some of the circuit must be left exposed where soldering is required such as surface mount tabs, connection holes etc.
The printed circuit board is now virtually complete and just needs finishing off. This involves cutting the board to size, electrical tested for open&short circuits as well as a manual eye inspection in QA process to ensure high quality.