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 install applications or through rilled holes in the board and copper pads for soldering the component leads in thru-hole applications. A board style may have all thru-hole parts on the top or part side, a mix of thru-hole and surface mount on the top only, a mix of thru-hole and surface install elements on the top side and surface install components on the bottom or circuit side, or surface install elements on the leading and bottom sides of the board.

The boards are likewise used to electrically link the required leads for each element using conductive copper traces. The element pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are designed as single agreed copper pads and traces on one side of the board only, double agreed copper pads and traces on the leading and bottom sides of the board, or multilayer styles with copper pads and traces on the top and bottom of board with a variable variety 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 etched away to form the actual copper pads and connection traces on the board surface areas as part of the board manufacturing procedure. A multilayer board consists of a number of layers of dielectric material that has actually been impregnated with adhesives, and these layers are utilized to separate the layers of copper plating. All of 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 technologies.

In a typical 4 layer board design, the internal layers are often utilized to provide power and ground connections, such as a +5 V plane 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. Really complicated board designs may have a a great deal of layers to make the numerous connections for different voltage levels, ground connections, or for linking the numerous leads on ball grid variety devices and other large integrated circuit bundle formats.

There are generally two kinds of material utilized to construct a multilayer board. Pre-preg product is thin layers of fiberglass pre-impregnated with an adhesive, and remains in sheet form, usually about.002 inches thick. Core material is similar to a really 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 density dielectric material with 1 ounce copper layer on each side. In a multilayer board design, there are two methods used to develop the preferred variety of layers. The core stack-up method, which is an older innovation, utilizes a center layer of pre-preg product with a layer of core product above and another layer of core product below. This mix of one pre-preg layer and 2 core layers would make a 4 layer board.

The film stack-up method, a more recent innovation, would have core product as the center layer followed by layers of pre-preg and copper material built up above and below to form the last number of layers required by the board style, sort of like Dagwood building a sandwich. This method allows the producer flexibility in how the board layer thicknesses are integrated to satisfy the ended up product density requirements by varying the variety of sheets of pre-preg in each layer. When the product layers are finished, the entire stack is subjected to heat and pressure that causes the adhesive in the pre-preg to bond the core and pre-preg layers together into a single entity.

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

The process of determining products, procedures, and requirements to satisfy the customer's requirements for the board design based on the Gerber file info supplied with the purchase order.

The process of transferring the Gerber file data for a layer onto an etch resist film that is placed on the conductive copper layer.

The conventional process of exposing the copper and other areas unprotected by the etch resist movie to a chemical that eliminates the unguarded copper, leaving the protected copper pads and traces in location; newer procedures use plasma/laser etching instead of chemicals to get rid of the copper material, allowing 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 product.

The process of drilling all the holes for plated through applications; a second drilling procedure is used for holes that are not to be plated through. Information on hole place and size is included 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 placed 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 process if possible due ISO 9001 Accreditation to the fact that 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 against environmental damage, offers insulation, protects versus solder shorts, and secures traces that run between pads.

The process of coating the pad areas with a thin layer of solder to prepare the board for the eventual wave soldering or reflow soldering procedure that will happen at a later date after the components have actually been placed.

The procedure of using the markings for part classifications and component describes to the board. Might be used to just the top side or to both sides if components are mounted on both leading and bottom sides.

The procedure of separating several boards from a panel of similar boards; this procedure also enables cutting notches or slots into the board if needed.

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

The process of looking for connection or shorted connections on the boards by methods using a voltage between different points on the board and determining if a current circulation occurs. Relying on the board complexity, this procedure might need a specially created test component and test program to integrate with the electrical test system used by the board manufacturer.