A few elements of PCB manufacturing procedure

A printed circuit board is an assembly of multiple layers of fiberglass sheets that are laminated with copper patterns. This platform is used for mounting electronic components in a manner that results in a product capable of performing a desired function.

Before the PCB manufacturing process could begin, a schematic diagram is prepared. The diagram is a depiction of the connections between various parts on board. Generally these boards have three types: single-sided, double-sided and multi-layered. The density of parts and circuit complexity determines which type will be used.

Materials like copper, nickel, and aluminum are used for backing the board. All of these are non-conductive. After plating the board with material, holes are created for the purpose of allowing the electric current to flow between the layers, and to connect the parts on it. Once drilling is finished, smaller conductor particles are removed by scrubbing the board.

This is followed by etching which promotes adhesion. After that an additional layer of conductive material is applied. Since holes that are drilled on the backing are not conductive, electrolysis copper plating process is performed to cover the holes with a conductive layer.

To achieve the final circuit design, and ideal thickness photo-imaging technique is used. This is done by electroplating cooper on the board. After this one more step of etching is performed, and to protect the final circuit a layer of lead or tin solder resist is applied. The tin or lead plating is removed so that the copper that will not be part of final circuit is exposed. To remove the unwanted copper solution like hydrogen peroxide are used.

Many volatile organic and photosensitive compounds are also used as resists. They can be applied in both wet and dry form. After being exposed to the UV light photosensitive compounds become hard. If the resist is applied in liquid form, techniques like silk screen, spray, roller and squeegee are used. Liquid resist is applied on either side, and it can even be applied on a specific surface area.

Inner layers cores are assembled for forming multi layered panels. The assembling is done in the form of book comprising multiple copper foil layers. The book is then exposed to high pressure and heat by putting in a lamination press. It melts the sheets of epoxies and results in the formation of a bond.  Panel is then buffed, trimmed and cured by placing in an over, and after that holes are drilled wherever necessary.