Printed Circuit Boards are manufactured through a combination of photo imaging and etching processes. The process outlined below is a general overview of how PCBs are manufactured. When they are manufactured in high volumes these steps are carried out differently to increase efficiency and reliability but it should give you a general idea.
Initially a schematic of the circuit is typically created using Computer Aided Design (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.
PCB materials such as FR4, Getek and Polymidec 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. For multilayer boards, each layer is simply added on top of another and then baked in the oven.
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. Some of the circuits on different layers will need connecting together, this is achieved using a process called “through hole plating”.
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 circuits and short circuits as well as a manual eye inspection to ensure high quality.