In electronics, printed circuit boards, or PCBs, are used to mechanically support electronic components which have their connection leads soldered onto copper pads in surface mount applications or through rilled holes in the board and copper pads for soldering the element leads in thru-hole applications. A board style might have all thru-hole components on the top or component side, a mix of thru-hole and surface mount on the top only, a mix of thru-hole and surface area mount parts on the top side and surface mount elements on the bottom or circuit side, or surface area mount parts on the top and bottom sides of the board.

The boards are also used to electrically link the needed leads for each component using conductive copper traces. The part pads and connection traces are engraved from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are created as single sided with copper pads and traces on one side of the board just, double sided with copper pads and traces on the leading and bottom sides of the board, or multilayer styles with copper pads and traces on top and bottom of board with a variable number of internal copper layers with traces and connections.

Single or double sided boards include a core dielectric product, such as FR-4 epoxy fiberglass, with copper plating on one or both sides. This copper plating is engraved away to form the real copper pads and connection traces on the board surface areas as part of the board manufacturing procedure. A multilayer board consists of a variety of layers of dielectric product that has actually been fertilized with adhesives, and these layers are used to separate the layers of copper plating. All these layers are aligned and then bonded into a single board structure under heat and pressure. Multilayer boards with 48 or more layers can be produced with today's innovations.

In a common four layer board design, the internal layers are frequently used to supply power and ground connections, such as a +5 V aircraft layer and a Ground aircraft layer as the two internal layers, with all other circuit and component connections made on the top and bottom layers of the board. Very complex board designs may have a large number of layers to make the different connections for different voltage levels, ground connections, or for linking the many leads on ball grid variety gadgets and other large integrated circuit bundle formats.

There are typically two kinds of material used to build a multilayer board. Pre-preg material is thin layers of fiberglass pre-impregnated with an adhesive, and remains in sheet form, usually about.002 inches thick. Core product resembles an extremely thin double sided board in that it has a dielectric product, such as epoxy fiberglass, with a copper layer transferred on each side, typically.030 thickness dielectric material with 1 ounce copper layer on each side. In a multilayer board style, there are 2 methods utilized to develop the preferred number of layers. The core stack-up approach, which is an older technology, uses a center layer of pre-preg material with a layer of core product above and another layer of core material listed below. This combination of one pre-preg layer and 2 core layers would make a 4 layer board.

The film stack-up technique, a more recent technology, would have core product as the center layer followed by layers of pre-preg and copper product developed above and below to form the last variety of layers required by the board design, sort of like Dagwood building a sandwich. This approach enables the manufacturer versatility in how the board layer densities are integrated to fulfill the ended up product density requirements by differing the variety of sheets of pre-preg in each layer. When the material layers are finished, the entire stack goes through heat and pressure that triggers the adhesive in the pre-preg to bond the core and pre-preg layers together into a single entity.

The procedure of producing printed circuit boards follows the steps below for many applications.

The procedure of figuring out products, processes, and requirements to fulfill the consumer's specifications for the board design based on the Gerber file details supplied with the order.

The procedure of transferring the Gerber file data for a layer onto an etch withstand movie that is put on the conductive copper layer.

The standard procedure of exposing the copper and other locations unprotected by the etch resist movie to a chemical that eliminates the vulnerable copper, leaving the secured copper pads and traces in location; more recent procedures utilize plasma/laser etching ISO 9001 instead of chemicals to eliminate the copper product, permitting finer line definitions.

The process of aligning the conductive copper and insulating dielectric layers and pressing them under heat to activate the adhesive in the dielectric layers to form a solid board material.

The process of drilling all the holes for plated through applications; a 2nd drilling procedure is utilized for holes that are not to be plated through. Information on hole area and size is consisted of in the drill drawing file.

The procedure of using copper plating to the pads, traces, and drilled through holes that are to be plated through; boards are positioned in an electrically charged bath of copper.

This is needed when holes are to be drilled through a copper location however the hole is not to be plated through. Prevent this procedure if possible since it includes cost to the finished board.

The procedure of applying a protective masking product, a solder mask, over the bare copper traces or over the copper that has had a thin layer of solder applied; the solder mask safeguards versus ecological damage, offers insulation, safeguards against solder shorts, and safeguards traces that run in between pads.

The procedure of covering the pad areas with a thin layer of solder to prepare the board for the ultimate wave soldering or reflow soldering procedure that will take place at a later date after the elements have been positioned.

The process of using the markings for element designations and element lays out to the board. Might be used to just the top side or to both sides if components are installed on both top and bottom sides.

The process of separating multiple boards from a panel of identical boards; this procedure likewise enables cutting notches or slots into the board if needed.

A visual evaluation of the boards; likewise can be the procedure of checking wall quality for plated through holes in multi-layer boards by cross-sectioning or other approaches.

The process of checking for connection or shorted connections on the boards by means applying a voltage between numerous points on the board and determining if a current flow happens. Relying on the board intricacy, this process might need a specially developed test fixture and test program to integrate with the electrical test system utilized by the board producer.